43 C.F.R. § 3108.40
A lease or interest therein may not be cancelled to the extent that such action adversely affects the title or interest of a bona fide purchaser even though such lease or interest, when held by a predecessor in title, may have been subject to cancellation. All purchasers will be charged with constructive notice as to all pertinent regulations and all BLM records pertaining to the lease and the lands covered by the lease. Prompt action may be taken to dismiss as a party to any proceedings with respect to a violation by a predecessor of any provisions of the Act, any person who shows the holding of an interest as a bona fide purchaser without having violated any provisions of the Act. No hearing will be necessary upon such showing unless prima facie evidence is presented that the purchaser is not a bona fide purchaser.
43 C.F.R. §3108.40